Information storing device and method for controlling same to record/reproduce information by selecting one of working modes

ABSTRACT

An information storing device and an information processing device having a memory for registering a plurality of working modes at recording/reproduction and a switching circuit for selecting one of the plurality of working modes, which select the optimum working mode automatically or by an instruction of an operator according to power supply capacity of a device of higher rank to effect recording/reproduction.

This is a continuation of application Ser. No. 09/408,167 filed on Sep.29, 1999, now U.S. Pat. No. 6,151,182, issued Nov. 21, 2000, which is acontinuation of application Ser. No. 08/931,071 filed Sep. 15, 1997,which is a continuation of application Ser. No. 08/469,121 filed Jun. 6,1995, abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to an information storing device, and inparticular to an information storing device having a plurality ofworking modes at recording/reproduction, which can be selected accordingto conditions of power supply for a device of higher rank, with whichthe information storing device is connected, and a method for drivingsame. The term “information storing device” used here includes a rotarytype information storing device such as a magnetic disk device, anoptical disk device, an opto-magnetic disk device, etc. and a magnetictape device.

The present invention can be applied to a mounted/dismounted type and afixed type information storing devices.

Down-sizing and diversification have been attempted also for rotary typeinformation storing devices such as a magnetic disk device, optical diskdevices, opto-magnetic disk devices, etc. and magnetic tape devices,used as external storing devices, keeping step with down-sizing ofelectronic computers such as so-called personal computers, officecomputers, work stations, etc. For example, down-sizing tendency ofmagnetic disk devices is such that it proceeds from 3.5″ to 2.5″, to1.8″ and further to 1.3″. Down-sizing tendency can be seen also foroptical disk devices and opto-magnetic disk devices. Hereinbelow theserotary type information storing devices are generally called simply diskdevices.

On the other hand, keeping step with down-sizing of the magnetic diskdevices, card type mountable/dismountable magnetic disk devicesaccording to PCMCIA (Personal Computer Memory Card InternationalAssociation) standard have been developed. For example, there are knowntechniques disclosed in U.S. Pat. No. 5,062,016, filed May 5, 1986,JP-A-5-181565 and further JP-A-4-356785.

As a representative specification, by which standardization is intended,including interface for electric connection, there is a recommendedspecification on IC memory card for personal computer promoted bycorporate Juridical Person, Japanese Electronic Industry DevelopmentAssociation (JEIDA), in cooperation with PCMCIA in USA. Originally itwas a recommended specification exclusively directed to memory card(PCMCIA Rel. 1.0/JEIDA Ver. 4.0). Thereafter it was extended to aspecification (PCMCIA Rel. 2.1/JEIDA Ver. 4.2), including magnetic diskdevices, keeping step with down-sizing of the magnetic disk devices.

According to this recommended specification on IC memory card forpersonal computer, working conditions can be set so that a relevantmemory card can be used together with other cards of an electroniccomputer system. According to the specification the system can be soconstructed that it is prohibited to use a PC card, when workingconditions offered by the PC card don't satisfy working conditionsrequired by the system.

A parameter on power condition information is included in these workingconditions. The parameter includes standard voltage of working power,minimum voltage of working power, maximum voltage of working power,current of continuous power, maximum value of mean current in 1 sec,maximum value of mean current in 10 millisec, necessary supplied currentin power down mode, etc.

The system, in which use of a PC card type magnetic disk device isexpected, is diversified.

That is, it extends from a work station having a sufficient power supplycapacity, which demands a high speed access property from the magneticdisk device, to a portable type computer incorporating a battery, whichdemands low power consumption rather than access property. Therefore itis desired for the PC card type magnetic disk device used over these notspecified but diversified devices of higher rank to be able to offerselectively a high speed access property or a low power consumptionaccording to power supply capacity of a device of higher rank connectedtherewith.

However, as it can be seen from the recommended specification for ICmemory card for personal computer published by JEIDA and PCMCIA in USA,there are no disk devices including a PC card type or a fixed type whichcan offer selectively a high speed access property or a low powerconsumption according to power supply capacity of the device of higherrank.

Personal computers of notebook size or pocket notebook size have beenused more and more often outside office owing to down-sizing ofcomputers, which has accelerated lowering of power consumption of diskdevices mounted on the computers. That is, it has been tried to lowerpower consumption according to the tendency that smaller driving powerof a disk device is more desirable. As an example thereof, there areknown techniques disclosed in U.S. Pat. No. 4,933,785 (correspondingJapanese application JP-B-3-503101), in which electric power supply tocircuits, for which no power is required functionally in each workingmode, is suppressed by constructing a magnetic disk device so thateither one of working modes can be set by classifying them into:

1) sleep mode, in which, least necessary interface function with adevice of higher rank (computer system) necessary for restarting CPUbeing left, other circuits or function thereof are stopped;

2) idle mode, in which CPU is working and, all interface functions withthe device of higher rank being left, function of a spindle motor, aservo motor, a record reproducing circuit, etc. is stopped;

3) idle mode, in which servo function is working in a state where thespindle motor is rotated and a data recording/reproducing circuit is ina stopped state; and

4) several working modes in usual operation such as a write/read mode, aseek mode, etc.

An effect to reduce mean power consumption in the different workingmodes can be achieved by this method. However, by this method, noattention is paid to the initial period of the spindle motor start, atwhich power consumption is maximum. For this reason, no effect can beobtained to reduce specifically power current at start of the diskdevice.

As other prior art techniques there are those disclosed inJP-A-4-205963.

By this method, the number of turns of the spindle motor is decreased tosuch a degree that the rotation of the disk is maintained in a waitingmode, in which write/read is not effected. This method has an effect toreduce the transient necessary maximum power current to shorten a periodof time necessary for increasing the rotation of the disk to apredetermined value.

However, in a disk device in general, frequency with which the statewhere write/read is not effected is produced is not necessarily so high.Further, since the state where write/read is not effected is one wherepower consumption is smallest next to the not working state (powerconsumption being 0 W) where power is not switched on (power consumptionis greatest at start of the motor and next greatest at file access, ineither case power consumption being greater than that required whenread/write is not effected while rotating the motor), as indicated in acited reference, even if the disk motor speed is reduced by setting awaiting mode in this state where read/write is not effected, no effectto reduce remarkably power consumption can be obtained as a whole. Onthe contrary, considerable power is consumed temporarily, because it isrequired to increase the rotation speed of the disk motor upto apredetermined value, when it proceeds from this waiting mode to awrite/read operation, if the read/write state is interrupted in thiswaiting mode.

Furthermore, since a certain period of time is required for increasingthe rotation speed of the motor upto the predetermined value when itproceeds from this waiting mode to the write/read operation, this givesrise to a problem that start of the write/read operation is retarded,which lowers working speed.

In addition, in this cited reference, read/write speed is only one usualspeed (one kind) and no attention is paid to set arbitrarily diversifieddata read/write speeds according to needs of users.

As another prior art example, there are known techniques, by which incase where the point of time of a succeeding read/write start ispreviously known in a magnetic disk device, it is avoided toaccelerate/decelerate the head more strongly than required to save powerat seek by detecting a waiting time from seek start to read/write startand by controlling seek speed (moving speed) of the head so that thedifference between this waiting time and an average seek time previouslyobtained for each displacement distance of the head be approximatelyzero, as described in JP-A-6-387663.

However no idea is disclosed to distinguish high speed seek, by whichhigh speed processing is possible, and low speed seek effected with lownoise and low power according to request of the user or according topower supply capacity of the device of higher rank. Further no attentionis paid to read/write arbitrary data with different read/write speedssuch as a high speed, a standard speed and a low speed according torequest of the user.

As a prior art example on the high speed access property, there areknown techniques, by which in order to improve operability of areproducing device in a compact disk (CD) or a digital audio taperecorder (DAT), a second speed is automatically set for read/write ofsignals such as control signals TOC other than audio signals, whichspeed is higher than read/write speed for usual audio signals, asdescribed e.g. in JP-A-2-156470. However, in this document, no attentionis paid to record/write arbitrary data which should be used by the userwith different medium speeds such as a high speed, a standard speed anda low speed or to lower power consumption according to request of theuser or according to power supply capacity of the device of higher rank.

For a magnetic head used in a magnetic disk device, heretofore aninductive head is used, which produces reading voltage on the basis ofthe electro-magnetic induction effect on winding conductor.

Recently an MR head is used, which produces reading voltage on the basisof the magneto-resistance effect. The MR head has a feature that itproduces reading voltage without variations in magnetic field intensitydue to relative movement of the magnetic head to a magnetic recordingface. Further for the magnetic head of hard disk drive, a floatingmethod is usually used, utilizing a hydromechanical effect actingbetween the head slider and the disk surface. In addition, recently acontact method called contact recording is used, by which the headslider, on which the magnetic head is mounted, is not floated.

Requirements of users for properties of a magnetic disk device or anoptical disk device can be roughly classified into two types, asdescribed below.

{circle around (1)} high speed transfer, high speed access, and

{circle around (2)} low power consumption, low noise.

In order to satisfy the requirements defined by {circle around (1)}, itis necessary to increase the read/write speed of the disk, i.e. therotation speed and the seek speed of the head. On the contrary, in orderto satisfy the requirements defined by {circle around (2)}, it isnecessary to decrease the read/write speed of the disk (rotation speed)and the seek speed of the head. These two properties are contradictoryto each other and there exists heretofore no disk device satisfyingthese two properties at the same time, but there are different models ofdevices, each of which has one kind of the data read/write speed and theseek speed. For this reason every user cannot help preparing at leastone model of devices satisfying each of the two properties and selectinga magnetic disk device having properties suitable for utilizationconditions (whether it is used under restriction on noise level andmaximum power, whether the transfer·access speed is regarded asimportant, etc.) for every use.

In this case problems as described below take place:

{circle around (1)} a magnetic disk device having either one of theproperties should be selected, even if aimed utilization conditions arenot clear;

{circle around (2)} there is no way other than buying another or replaceby another, when it is desired to exchange a property of a magnetic diskdevice with another in the course of utilization because of change inutilization conditions; and

{circle around (3)} it is impossible to switch over the propertiestimely according to way of utilization.

Particularly such problems take place for a disk device attached to apersonal computer using both a commercial AC power source and anincorporated battery power source such as e.g. a notebook type personalcomputer. In this kind of personal computers, since sufficient power canbe supplied in case where a commercial AC power source is used, it isdesirable to keep the head seek speed and the disk read/write speedsatisfactorily high. On the other hand, in case where an incorporatedbattery power source is used, it is desirable to lower the head seekspeed and the disk read/write speed to use it at a low power consumptionin order to elongate continuous utilization time of the system.

However there exist no information storing devices yet, which can beused while switching working modes of access or read/write according toutilization conditions.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an information storingdevice having a function to effect a high speed processing of theinformation storing device while making positively efficient use ofpower, when enough power is disposable and to drive the informationstoring device at various low power consumption modes, when disposablepower is not enough, according to power conditions of the device ofhigher rank, with which the information storing device is connected.

Concretely speaking, it is to provide an information storing devicewhich selects itself or has a device of higher rank select a high speedaccess property, a high speed processing property or a low powerconsumption property according to power supply capacity thereof for wideranging devices of higher rank

1) from work stations having sufficient power supply capacities,demanding a high speed access property and a high speed processingproperty to the disk device

2) to battery incorporating portable type electronic computers demandinglow power consumption rather than access property, etc, and performsread/write operations with the selected operation or working mode.

Another object of the present invention is to provide a disk devicecapable of removing the problems of the prior art techniques, by which auser can select arbitrarily one of at least two modes, which are a quickmode (high speed transfer·high speed access mode) for effecting seek anddata read/write and a silent mode (low speed·low power consumption·lownoise mode).

Still another object of the present invention is to provide a diskdevice having a switching function acting so as to select the quick modein case where a commercial power source is used and the silent mode incase where an incorporated battery power source is used in a disk deviceattached to a personal computer, in which both the commercial powersource and the incorporated battery power source is used.

In order to achieve the above objects an information storing deviceaccording to the present invention is constructed as follows.

The information storing device provided with means for inputting powerfrom a device of higher rank; a device for selecting one of workingmodes having different necessary maximum currents; and a device forinforming the device of higher device of necessary maximum currentinformation on each of the selectable working modes.

Particularly in a device using a disk-shaped memory medium theselectable working modes are composed of combinations of:

1) different disk rotation speeds;

2) different average seek times; and

3) different times for starting the spindle motor.

In case where a magnetic tape is used, various working modes arerealized by making speeds of fast forwarding and rewinding different.

Further a read head for reading out signals from data recorded in a diskmay be an MR head using a magneto-resistance effect element. Inaddition, the contact recording method may be used, by which themagnetic head is not floated by the hydromechanical effect between theslider, on which the read head is mounted, and the surface of themagnetic disk in a region of the rotation speed of the magnetic disk inthe selectable working modes.

The information storing device may comprise further a device forreceiving information on current, which the device of higher rank cansupply, from the device of higher rank, with which it is connected, anda device for prohibiting execution of the working modes, in which thenecessary maximum current is greater than the current, which can besupplied, among the plurality of working modes.

On the other hand the device of higher rank includes a device forsupplying electric power to the information storing device; a device forreceiving the maximum current information of the plurality of selectableworking modes having different necessary maximum currents; a device fordetecting or calculating current, which the device feeding with electricpower can supply, taking utilization situations into account; a devicefor selecting a specified working mode among the plurality of workingmodes; and a device for prohibiting that the working modes, in which thenecessary maximum current is greater than the current, which can besupplied, are selected among the plurality of working modes.

An important effect can be obtained particularly in case where a powersource (battery) is incorporated in the device of higher rank.

When a working mode, in which the necessary maximum current of theinformation storing device is greater than the current which can besupplied by the device feeding with electric power in the device ofhigher rank, is selected, either one or a plurality of followingpredetermined operations are effected, before electric power is suppliedin reality e.g. for starting the spindle motor in the connectedinformation storing device:

1) it is prohibited to select the specified working modes;

2) it is displayed to an operator that the specified working modes areincluded; and

3) a selectable working mode is executed.

By a method for controlling the device of higher rank and theinformation storing device, the device of higher rank is informed by theinformation storing device of the necessary maximum current informationon each of the plurality of selectable working modes before the start ofthe spindle motor, which is an operation giving the greatest current,thereafter the information storing device receives a control signal forselecting one of the plurality of working modes from the device ofhigher rank, and the start and normal rotation of the spindle motor oroperation for positioning the read head is effected according to theworking mode thus selected.

By another control method, when the information storing device receivesthe command to start the spindle motor from the device of higher rank,while the information storing device informs the device of higher rankof the necessary maximum current information several times in apredetermined order, it stops to inform the device of higher rank of thenecessary maximum current information and at last begins the start ofthe spindle motor in the working mode, for which the device of higherrank is informed of the necessary maximum current information.

Particularly, in an information storing device using a magnetic tape,the operation for selecting the working mode is effected before thestart of the tape forwarding.

Further, in order to achieve the above objects, a disk device accordingto the present invention is constructed as follows.

(1) A disk device, in which a disk-shaped recording medium is rotatedand at the same time a head is moved towards an aimed position on therecording medium to record data in the recording medium or to reproducethe data therefrom, comprises a head moving speed mode switching device,which switches the seek moving speed of the head by more than two steps,and a medium rotation speed mode switching device, which switches therotation speed at recording or reproduction of the recording medium bymore than two steps.

(2) A disk device according to (1) is so constructed that switching ofthe seek moving speed of the head and switching of the rotation speed ofthe recording medium are effected according to a command from the deviceof higher rank.

(3) A disk device according to (1) or (2) is so constructed that it hasboth a commercial power source and an incorporated battery power sourceand that the device for switching the head moving speed mode and thedevice for switching medium rotation speed mode switch both the seekmoving speed of the head and the rotation speed of the recording mediumto high speed mode, when the commercial power source is used, and boththe seek moving speed of the head and the rotation speed of therecording medium to low speed mode, when the incorporated battery powersource is used.

Operation based on the construction will be explained below.

According to the construction described in (1), since the seek movingspeed of the head and the rotation speed of the recording medium (disk)can be switched by more than two steps, when a user wishes to effectread/write of signals at a high speed with one disk device, he canread/write in a state where the quick mode (both the head and the diskat the highest speeds) is selected, and on the contrary, when he wishesto reduce noise and power consumption, he can read/write in a statewhere the silent mode (both the head and the disk at the lowest speeds)is selected. Since the working mode can be selected arbitrarily, asdescribed above, {circle around (1)} even if utilization conditions arenot previously determined, it is possible to select a working modesuitable to utilization conditions determined thereafter; {circle around(2)} even if utilization conditions are changed, it is unnecessary topurchase any new disk device; and further {circle around (3)} even inthe course of utilization the user can change the working mode inaccordance with utilization conditions.

If a speed mode switching mechanism is so constructed that modeswitching is effected by a command from the device of higher rank to amicroprocessor in the disk device according to the constructiondescribed in (2) so that the user can select a suitable mode freely atany time, the user can select a desired mode simply by key operation,etc. Further, instead thereof, The switching of the mode can be effectedalso by means of a switch of hardware such as a jumper connectordisposed on a head driving circuit and a disk motor driving circuit inthe disk device.

According to the construction described in (3), in case where acommercial power source is used for power supply of a personal computerand a disk device, the quick mode of high speed read/write and highspeed seek is selected so that data transfer/access of high speed andhigh performance can be effected. On the contrary, in case where anincorporated battery power source is used, the silent mode of low speedread/write and low speed seek is selected so that data transfer/accesscontinuously operable for a long time can be effected with a low noiseand a low power consumption.

Following advantages can be obtained by the information storing deviceaccording to the present invention.

Higher access property, higher starting property, and higher tapeforwarding property can be achieved according to capacity of the powersource.

Further, by using an MR head, since influences of variations in therotation speed of the magnetic disk on the read signal are kept small,effects of the different working modes having different rotation speedsof the magnetic disk can be more efficient.

Furthermore, by using a not floated magnetic head, since influences ofvariations in floating amount on the read signal are kept small, effectsof the different working modes having different rotation speeds of themagnetic disk can be more efficient.

Since the operator can select arbitrarily one of the selectable workingmodes to execute and also since the device of higher device can selectsuitably one working mode to execute, an effect can be obtained tointend efficient utilization of the incorporated power source.

An effect can be obtained that it is possible to effect driving andcontrol of the information storing device suitable for power supplycapacity of the device of higher rank. Consequently, in case where theincorporated power source is a battery, an effect can be obtained thatit is possible to elongate utilization time of the battery.

According to the present invention it is possible to use widely not onlya magnetic disk device compatible with the PC card standard but alsoother information storing devices. That is, it is possible to provide aninformation storing device, a device of higher rank thereof and a methodfor controlling same, which can offer a high speed access property or alow power consumption property according to power supply capacity ofwide ranging devices of higher rank from work stations having sufficientpower supply capacity and requesting high speed access property from theinformation storing device to battery incorporating portable computerdevices requesting low power consumption rather than access property.

Further, according to the present invention, since one disk device is soconstructed that the seek speed of the head and the rotation speed ofthe disk recording medium can be switched by more than two steps, aneffect can be obtained that the working mode can be selected arbitrarilyaccording to request of a user, e.g. the silent mode of low speed isselected, when file access and data transfer of low noise and low powerconsumption are desired, while the quick mode is selected, when highspeed file access and data transfer are desired. Further, since no priorart waiting mode (waiting mode, in which the rotation speed of the diskmotor between different accesses to read/write is lower than therotation speed at read/write) is adopted, an effect can be obtained thatno operation for increasing (raising) the rotation speed of the motorupto a predetermined value at successive data accesses is necessary andtherefore no delay in the read/write operation due to this operation forincreasing the rotation speed of the motor upto the predetermined valueis produced.

Further an effect can be obtained that a user can select easily arequired mode, if selection and switching of these working modes areeffected by the device of higher rank.

Furthermore, in case where the present invention is applied to apersonal computer, in which both a commercial power source and anincorporated battery power supply are used, such as a notebook typepersonal computer, an effect can be obtained that it can be usedproperly according to utilization conditions, because when thecommercial power source is used, since the quick mode of high speedread/write and high speed seek is selected, it is possible to effectdata transfer and access of high speed and high performance, and on thecontrary, when the battery power source is used, since the silent modeof low speed read/write and low speed seek is selected, a long timecontinuous operation can be effected with low noise and low powerconsumption, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a disk device according to the presentinvention;

FIG. 2 is a perspective view of the disk device according to the presentinvention, a battery incorporating information processing device and awork station computer device, in each of which the disk device is used;

FIG. 3 is a diagram indicating specification of different working modesof the disk device according to the present invention;

FIG. 4 is a diagram indicating current waveforms at starting differentworking modes;

FIG. 5 is a block diagram indicating a connection relation between thedisk device and the battery incorporating information processing device;

FIG. 6 is a diagram indicating a relation between position and floatingamount of a magnetic head;

FIG. 7 is a diagram indicating reading outputs for different types ofmagnetic heads;

FIG. 8 is a flow chart showing an embodiment of starting procedure onthe disk device side according to the present invention;

FIG. 9 is a flow chart showing another embodiment of starting procedureon the disk device side according to the present invention;

FIG. 10 is a flow chart showing an embodiment of starting procedure ofthe disk device on the device of higher rank side according to thepresent invention;

FIG. 11 is a flow chart showing still another embodiment of startingprocedure on the disk device side according to the present invention;

FIG. 12 is a flow chart showing an embodiment of starting procedure onthe magnetic tape device side according to the present invention;

FIG. 13 is a flow chart showing another embodiment of starting procedureof the disk device on the device of higher rank side according to thepresent invention;

FIG. 14 is an example of display indicating relation between currentwhich can be supplied and the working mode;

FIG. 15 is a block diagram of a disk device having a working modeturning-over switch according to the present invention;

FIG. 16 is a block diagram of another embodiment of the disk deviceaccording to the present invention having a working mode switchingcircuit within CPU;

FIG. 17 is a block diagram of still another embodiment of the diskdevice according to the present invention having a working modeswitching circuit within CPU, and a current limiting circuit for each ofmotor driving circuits;

FIG. 18 is a block diagram of still another embodiment of the diskdevice according to the present invention having a working modeswitching circuit within CPU, and a current limiting circuit for each ofa head driving circuit and a motor driving circuit;

FIG. 19A is a graph indicating variations in rotation speed of a motorat motor start;

FIG. 19B is a graph indicating variations in current flowing through themotor at motor start;

FIG. 20A is a graph indicating variations in head moving speed at motorstart and stop;

FIG. 20B is a graph indicating variations in current flowing through ahead driving circuit at motor start; and

FIG. 21 a flow chart for explaining a working relation between the diskdevice and the device of higher rank according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinbelow an embodiment of the present invention will be explained,referring to several diagrams and tables.

FIG. 1 is a perspective view of a disk device which is an embodiment ofthe present invention.

Explanation will be made taking a mountable/dismountable magnetic diskdevice as an example of the disk device. Of course, the presentinvention can be applied to a fixed type disk device. Outer sizes of thewhole disk device 101 are: width W=54 mm, depth D=85.6 mm and heightH=10.5 mm. Outer sizes of a card-shaped portion 102 are: width W=54 mm,depth D=85.6 mm and height H=3.3 mm. A connector portion 103 is composedof 68 pins, including power lines and data command lines. These areconsistent with Type 3 of the IC memory card specification for personalcomputer standardized according to PCMCIA/JEIDA.

FIG. 2 shows a mode of utilization of the disk device 101.

There is disposed a slot 203 for inserting an IC memory card in each ofa power source incorporating information processing device 201 and awork station computer device 202.

The power source incorporating information processing device 201 is aportable low power consumption type computer device, which is providedwith the slot 203 for inserting an IC memory card of Type 3, a foldawaydisplay plate, a hand writing input plate, a hand writing input pen, andinput keys. The work station computer device 202 is a desk highperformance computer device, which is also provided with a slot 203 forinserting an IC memory card of Type 3. The disk device 101 ismountable/dismountable on/from a device of higher rank provided with aslot 203 for inserting an IC memory card such as a power sourceincorporating information processing device 201, a work station computerdevice 202, etc.

FIG. 3 shows working modes of the disk device, which is an embodiment ofthe present invention.

Average access time and starting time can be cited as access property ofthe disk device. The average access time is a sum of average rotationwaiting time and average seek time.

In the working mode of a prior art magnetic disk device there was onlyone kind of 0.6 A mode. In this working mode the starting time took 3sec, including the rotation starting time necessary for the rotationspeed to reach 4464 rpm. The average rotation waiting time was 6.7 msec,which is a time corresponding to ½ turn at a disk rotation speed of 4464rpm. The average seek time was 16 msec and the average access time was22.7 msec.

There are three kinds of working modes classified by the requiredmaximum current, including a complete set of spindle motor startingoperation, read operation and head track seek operation, which are 0.6 Amode, 0.9 A mode and 1.5 A mode. The access property in the 0.6 A modeis identical to that obtained in the working mode of the prior art diskdevice.

In the 0.9 A mode, the starting time and the average seek time areimproved. The starting time is 2 sec, including the rotation startingtime necessary for the rotation speed to reach 4464 rpm. The averagerotation waiting time is 6.7 msec, which is a time corresponding to ½turn at a disk rotation speed of 4464 rpm, the average seek time is 8msec and the average access time is 14.7 msec.

In the 1.5 A mode, in addition, the average rotation waiting time isimproved. The starting time is 2 sec, including the rotation startingtime necessary for the rotation speed to reach 8928 rpm. The averagerotation waiting time is 3.4 msec, which is a time corresponding to ½turn at a disk rotation speed of 8928 rpm, the average seek time is 8msec and the average access time is 11.4 msec. FIG. 4 shows variationsin the starting current of the disk device, which is an embodiment ofthe present invention corresponding thereto.

FIG. 4 shows that maximum current is required at a initial period ofdrive of the spindle motor, depending on the starting mode. When thespeed is increased in the seek operation, required current is alsoincreased and increase of electric power required for initial drive ofthe spindle motor is greater.

FIG. 5 shows a block diagram of the power source incorporatinginformation processing device 201 and the disk device 101, which are anembodiment of the present invention. Even if no power source isincorporated in the information processing device 201, the presentinvention can be applied thereto.

The disk device 101 is connected with the power source incorporatinginformation processing device 201 through a connector portion 103 bymeans of power supply lines and data/command buses.

A drive control portion 603 in the disk device 101 includes CPU, RAM,ROM, etc. and effects rotation control of a spindle motor 608, headpositioning control through control of a voice coil motor 606,read/write control through a read/write head 607, etc. on the basis of acontrol program in the ROM 604. The control program in the ROM 604includes three kinds of drive control programs, in which the requiredmaximum currents are 0.6 A, 0.9 A and 1.5 A, respectively, correspondingto the working mode of the disk device, which is an embodiment of thepresent invention indicated in FIG. 3.

The read/write head 607 included in HDA (head disk assembly) 605 of thedisk device 101 may be used also by the contact recording method.Further an MR reading head 606 using a magneto-resistive element may beused therefor.

The power source incorporating information processing device 201 hasCPU, ROM and RAM in a control portion 31, determines how much current apower control portion 32 can supply to the disk device 101 and informsthe disk device 101 of results thus obtained through an interfaceportion 33 and a connector 38. 34 is an incorporated power source; 35 isa display portion; and 36 is an input portion manipulated by anoperator. 37 is an external power voltage detecting portion connectedwith control portion 31. When the external power is not supplied, thepower system is switched to incorporated power source 34 by controlportion 31.

As indicated by a graph representing variations in floating amount ofthe magnetic head (including both an inductive magnetic head and an MRmagnetic head) in FIG. 6, when the head floating method is used, it isdifficult to avoid variations in floating amount due to difference inthe disk rotation speed and difference in the inner and outer peripherallinear speed of the head. On the contrary, by the contact recordingmethod no variations in floating amount are produced. For this reason itis not necessary to compensate variations in spacing loss, variations ineffective gap loss and variations in amplitude-frequency characteristicsdue thereto in the magnetic-electric transforming reproduction process,which are produced by the floating method.

Therefore the contact recording method is suitable for the disk device,which is an embodiment of the present invention working with a pluralityof rotation speeds.

FIG. 7 shows reading output of the magnetic heads.

As indicated thereby, when the inductive magnetic head is used, it isdifficult to avoid variations in amplitude-frequency characteristics,i.e. variations in the reading output, in the magnetic-electrictransforming reproduction process due to differences in rotation speedsof the magnetic head and the magnetic disk. On the contrary, sincevariations in the reading output are small for an MR reading head, nocompensating circuit therefor is necessary. The MR reading head issuitable for the magnetic disk device, which is an embodiment of thepresent invention working with a plurality of rotation speeds.

FIG. 8 is a flow chart showing a procedure for starting the disk device,which is an embodiment of the present invention.

In the disk device initialization is effected (Step 51) after start ofpower supply from the battery incorporating information processingdevice, which is the device of higher rank thereof. Thereafter ittransmits the information on maximum currents Imax required in thedifferent working modes to the device of higher rank in a predeterminedorder. In the present embodiment it is transmitted in an order of 1.5 A,0.9 A and 0.6 A, i.e. with decreasing maximum current. Thereforeinformation of 1.5 A is offered at first (Step 52). Then it waits for astart command from the device of higher rank allowing an operation inthe 1.5 A working mode for a predetermined time (Step 53). When thestart command has been received, the 1.5 A working mode is set (Step 54)to start the spindle motor (Step 61) and to effect an initial seekoperation (Step 62). When the start has been terminated, this isreported (Step 63) and it waits for read/write and other commands ofhigher rank (Step 64). One of the other commands of higher rank is e.g.a command of changing the working mode. When this command has beenreceived, the procedure returns to Step 51 to set a new working mode. Ifit receives a command of read/write, it executes that command (Step 65)and the procedure returns to Step 64 to wait for a succeeding command.

If no start command in the 1.5 A working mode has been received when apredetermined period of time has lapsed, 0.9 A information is offered tothe device of higher rank (Step 55). Then it waits for a start commandfrom the device of higher rank allowing an operation in the 0.9 Aworking mode for a predetermined time (Step 56). When the start commandhas been received, the 0.9 A working mode is set (Step 57) to effect aseries of the operations defined in Steps 61 to 65. If no start commandin the 0.9 A working mode has been received when a predetermined periodof time has lapsed, 0.6 A information is offered to the device of higherrank (Step 58). Then it waits for a start command from the device ofhigher rank allowing an operation in the 0.6 A working mode for apredetermined time (Step 59). When the start command has been received,the 0.6 A working mode is set (Step 60) to effect a series of theoperations defined in Steps 61 to 65.

If no start command in the 0.6 A working mode has been received when apredetermined period of time has lapsed, it is checked whether themaximum current information has been transmitted to the device of higherrank repeatedly a predetermined number of times or not (Step 66). Incase where it has been not transmitted thereto repeatedly apredetermined number of times, the procedure returns to Step 52 torepeat a series of transmission operations. On the contrary, if it hasbeen transmitted thereto repeatedly a predetermined number of times, theprocedure is terminated.

In the embodiment indicated in FIG. 8, once a working mode is set, theoperation is continued in the same working mode, until either the powersupply is switched off or a command of changing the working mode isreceived.

FIG. 9 shows another embodiment, in which power supply capacity of thedevice of higher rank is used most efficiently. Power supply conditionsof the device of higher rank are not always constant. In case where thedevice of higher rank drives a number of peripheral devices connectedtherewith, the power supply capacity thereof to the disk device issmall. On the contrary, in case where it drives few peripheral devices,the power supply capacity thereof to the disk device is great.Consequently, in the embodiment indicated in FIG. 9, the disk deviceinquires at every opportunity of the device of higher rank about thepower supply conditions thereof and works in a low performance workingmode, in which power consumption is small, when the power supplycapacity of the device of higher rank is small, while it works in thehigh performance working mode, changing the working mode, when the powersupply capacity of the device of higher rank is great.

Differences from the procedure indicated in FIG. 8 are that theprocedure returns to Step 52 after execution of the command in Step 65and that operation is effected in a working mode with a speed as high aspossible, every time a command of higher rank is issued.

FIG. 10 shows a processing flow of the power source incorporatinginformation processing device acting as a device of higher rank,corresponding to the operations of the disk device indicated in FIGS. 8and 9.

When power source is switched on, power supply to the disk device isstarted (Step 71). The maximum current information from the disk deviceis taken-in (Step 72) and it is checked whether the current Imax thustaken-in can be supplied or not (Step 73). If it can be supplied, astart command is issued (Step 74). If it cannot be supplied, theprocedure proceeds to Step 75 and it is checked whether information of aseries of currents is taken-in a predetermined number of times or not.In case where it is not taken-in a predetermined number of times, theprocedure returns to Step 72 and current information transmittedsucceedingly thereto is taken-in. If it is verified in Step 75 that ithas been taken-in the predetermined number of times, power supply to thedisk device is interrupted (Step 76) and the start of the disk device isstopped. In case where the start is stopped, it may be displayed in Step76 that the connected disk device cannot be driven by this device ofhigher rank.

FIG. 11 shows a processing flow indicating another embodiment of thestarting procedure of the disk device 101.

FIG. 11 corresponds to the case where the predetermined number is set at2 in Step 66 in FIG. 8. In the embodiment indicated in FIG. 11, theinformation on a series of necessary maximum currents is transmitted atleast twice to the device of higher rank. It is possible also that, onthe device of higher rank side, when the information on the series ofnecessary maximum currents is first received, nothing is selected and itis monitored what current is requested and when it is secondly received,an arbitrary working mode, in which power can be supplied, is selectedfrom the information on the series of necessary maximum currents andsent to the disk device. Steps 81 to 89 are identical to Steps 52 to 60,respectively.

FIG. 12 shows a starting procedure of a magnetic tape device. Content ofthe operation is basically identical to that indicated in FIG. 11.Operation steps having same contents are referred to by same stepnumbers.

When power is supplied from an external device, which is the device ofhigher rank, to the tape device, it is initialized (Step 91). Theninformation on necessary maximum currents is transmitted to the deviceof higher rank in an order of decreasing currents and the tape devicewaits for a starting command from the device of higher rank, every timeit is transmitted (Steps 52 to 59). When a starting command of 1.5 Aworking mode is received in Step 53, a high speed forwarding/rewindingworking mode is set (Step 92). When a starting command of 0.9 A workingmode is received in Step 56, a middle speed forwarding/rewinding workingmode is set (Step 93). When a starting command of 0.6 A working mode isreceived in Step 59, a low speed forwarding/rewinding working mode isset (Step 94). The Steps 94, 95 and 96 in the second current informationtransmission cycle correspond to the Steps 92, 93 and 94, respectively.

When the working mode is set, the tape device waits for a succeedingcommand of higher rank (Step 98). When the command is received, fastforwarding/rewinding is effected in the mode thus set and processing ofread/write and other commands (Step 99) is executed. Thereafter theprocedure returns to Step 98.

If the device of higher rank side responds during the first transmissioncycle of the information on the series of currents, the followingtransmission cycles of the information on currents are not executed,after the corresponding starting command has been received. It ispossible also that, on the device of higher rank side, when theinformation on the series of necessary maximum currents is firstreceived, nothing is selected and it is monitored what current isrequested and when it is secondly received, an arbitrary working mode,in which power can be supplied, is selected from the information on theseries of necessary maximum currents and sent to the magnetic tapedevice.

The tape device can be operated at a working mode with a speed as highas possible, every time a command of higher rank is issued, byconstructing the procedure so as to return to Step 52 after Step 99 inFIG. 12.

Further there is a command of changing the working mode among othercommands processed in Step 99. When the operator commands to issue thiscommand, the procedure returns to Step 52 and thus the working mode canbe set again in accordance with power supply conditions of the device ofhigher rank.

FIG. 13 shows a processing flow indicating an embodiment, in which alsothe operator can select the working mode.

When the power source is switched on, power is supplied from the powersource incorporating information processing device, which is the deviceof higher rank, to the disk device (Step 121). On the disk device side,when power is supplied, information on a series of necessary maximumcurrents Imax is offered to the device of higher rank once or byrepetition of two times, as indicated in FIG. 8 or FIG. 11. In this casethe currents are sent in a decreasing order.

On the device of higher rank side the maximum current information fromthe disk device is taken-in (Step 122) and it is checked whether thecurrent Imax thus taken-in can be supplied or not (Step 123). When itcan be supplied, a start command is issued (Step 124). When currentaccording to the first received current information cannot be supplied,information on a series of currents is taken-in in Steps 125 and 126. Atable showing a relation between the current which can be supplied andthe working mode, and a request of input of an instruction from theoperator to select the working mode is displayed (Step 127), asindicated in FIG. 14. Then the disk device waits for the instructionfrom the operator (Step 128). The operator sees the display indicated inFIG. 14 and selects a drivable working mode. After it has been judged inStep 123 that the current according to the current information cannot besupplied, the disk device is controlled so as not to accept the secondcurrent information and followings in Step 122.

In this way the operator can select a desired working mode to start thedisk device, after he has recognized selectable working modes of thedisk device.

The disk device may be one of various devices, such as a magnetic diskdevice, an optical disk device, an opto-magnetic disk device, etc. andthe present invention can be applied to any one of them.

Although a disk device is taken as an example if FIGS. 13 and 14, thepresent invention can be applied also to a magnetic tape device.

FIG. 15 shows another embodiment of the disk device according to thepresent invention, in which the working mode is set by means of aswitch.

In FIG. 15, a disk device 1 comprises a magnetic disk 2 acting asrecording medium; a motor 3 supporting rotatably the disk 2; a head 5for reading/writing signals from/in the disk 2; a head driving mechanism6; a motor driving circuit 4 for driving the motor 3; and a head drivingcircuit 7 connected with the head driving mechanism 6. Both the drivingcircuits 4 and 7 are connected with a CPU 8 and ROM 8 b and RAM 8 c areconnected with the CPU 8.

At least one switch 9 to 12 is connected with the CPU 8. In the caseindicated in FIG. 15 four switches are connected therewith. Variousworking modes can be set by combining these switches, as describedlater.

Two working modes are set within the CPU 8, one of which is a quickmode, in which the motor rotation speed is 7200 rpm and the seek movingtime of the head is 8 ms, while the other is a silent mode, in which themotor rotation speed is 5400 rpm (current at starting being same as inquick mode) and the seek moving time of the head is 10 ms (accelerationand deceleration being same as in quick mode). The quick mode is a mode,in which a high speed transfer and a high speed access can be realizedin the disk device, while the silent mode is a mode, in which a lowpower consumption and a low noise can be realized.

The two modes are designed so as to be able to be selected by settingthe switches 9 to 12 connected with the CPU 8. For example, when theswitch 9 is set at an OFF state, the working mode is the quick mode,while when it is set at an ON state, the disk device is operated in thesilent mode. In the case indicated in FIG. 15, since four switches 9 to12 are connected in FIG. 15, upto 24 different working modes can be setby combining these switches. In the case, indicated in FIG. 15, sincesetting of the working mode is effected by means of the switches 9 to12, such as e.g. jumper switches, disposed on the disk device, theycannot be set by commands from the device of higher rank (system).

FIG. 16 shows an outline of the construction of the disk device, whichis a second embodiment of the present invention, provided with a drivingcircuit effecting switching of the working mode by commands from thedevice of higher rank (system).

In FIG. 16, a disk device 1 comprises a disk 2 acting as recordingmedium; a motor 3 supporting rotatably the disk 2; a head 5 forreading/writing signals from/in the disk 2; a head driving mechanism 6;a motor driving circuit 4 for driving the motor 3; and a head drivingcircuit 7 connected with the head driving mechanism 6. Both the drivingcircuits 4 and 7 are connected with a CPU 8 and ROM 8 b and RAM 8 c areconnected with the CPU 8.

Two working modes, which are a quick mode and a silent mode, are setwithin the CPU 8 and a switching circuit 15 for switching these twoworking modes by commands from the device of higher rank (system) isincorporated. The switching circuit 15 within the CPU 8 is equivalent tothe switching circuits 9 to 12 indicated in FIG. 15, but it isconstructed by logic circuits so that various working modes aredetermined by a setting state of input data thereto.

FIG. 17 shows an outline of the construction of the disk device, whichis another embodiment of the present invention, in which a currentlimiting circuit 16 is incorporated in a CPU 8.

In FIG. 17, a disk device 1 comprises a disk 2 acting as recordingmedium; a motor 3 supporting rotatably the disk 2; a head 5 forreading/writing signals from/in the disk 2; a head driving mechanism 6;a motor driving circuit 4 for driving the motor 3; and a head drivingcircuit 7 connected with the head driving mechanism 6. Both the drivingcircuits 4 and 7 are connected with the CPU 8 and ROM 8 b and ROM 8 care connected with the CPU 8.

Two working modes, which are a quick mode and a silent mode, are setwithin the CPU 8 and further a switching circuit 15 for switching thesetwo working modes by commands from the device of higher rank and acurrent limiting circuit 16 determining separately maximum currentsflowing through the two driving circuit 4 and 7 are incorporated.

The maximum currents determined by the current limiting circuit 16 arelinked with the working mode selected by setting the switching circuit15. For example, in case where the quick mode is selected, the maximumcurrent is not limited, current flowing through the motor drivingcircuit 4 being 2 A and current flowing through the head driving circuit7 being 0.9 A (values determined by respective voltage and resistance),while in case where the silent mode is selected, the maximum currentsare so selected that current flowing through the motor driving circuit 4is 1.5 A and current flowing through the head driving circuit 7 is 0.6A.

FIG. 18 shows an outline of the construction of the disk device, whichis another embodiment of the present invention, in which currentlimiting circuits 17 and 18 are incorporated in different drivingcircuits 4 and 7, respectively.

In FIG. 18, a disk device 1 comprises a disk 2 acting as recordingmedium; a motor 3 supporting rotatably the disk 2; a head 5 forread/write signals from/in the disk 2; a head driving mechanism 6; amotor driving circuit 4 for driving the motor 3; and a head drivingcircuit 7 connected with the head driving mechanism 6. Both the drivingcircuits 4 and 7 are connected with the CPU 8 and ROM 8 b and ROM 8 care connected with the CPU 8.

Two working modes, which are a quick mode and a silent mode, are setwithin the CPU 8 and further a switching circuit 15 for switching thesetwo working modes by commands from the device of higher rank (system) isincorporated.

The maximum currents determined by the current limiting circuits 17 and18 are linked with the working mode selected by setting the switchingcircuit 15. For example, in case where the quick mode is selected, themaximum current is not limited. In this case the motor 3 and the headdriving mechanism 6 are driven by the driving circuits 4 and 7,respectively, and the maximum currents flowing through the drivingcircuits 4 and 7 are so set that current flowing through the motordriving circuit 4 is 2 A and current flowing through the head drivingcircuit 7 is 0.9 A (values determined by respective voltage andresistance), while in case where the silent mode is selected, themaximum currents are so set that the motor 3 and the head drivingmechanism 6 are driven by current flowing through the motor drivingcircuit 4 of 1.5 A and current flowing through the head driving circuit7 of 0.6 A, respectively. Consequently each of the motor driving circuitand the head driving circuit can be set in two different ways, butcontent of operation thereof is equivalent to that described for thedriving circuit in FIG. 17.

FIGS. 19A and 19B show variations in the rotation speed (FIG. 19A) andthe current (FIG. 19B), respectively, at starting the disk motor (untilthe rotation speed reaches a stationary state) in the above embodiment.

Solid lines indicate variations in the motor rotation speed v and thecurrent I, respectively, with respect to lapse of time in a quick mode,corresponding to the quick modes in FIGS. 15, 16, 17 and 18.Chain-dotted lines indicate variations in the motor rotation speed andthe current, respectively, with respect to lapse of time in a silentmode without current limitation, corresponding to the silent modes inFIGS. 15 and 16. Broken lines indicate variations in the motor rotationspeed and the current, respectively, with respect to lapse of time in asilent mode with current limitation, corresponding to the silent modesin FIGS. 17 and 18. Although operations at motor start are indicated inFIGS. 19A and 19B, when the motor is stopped, operation is inversed.

FIGS. 20A and 20B show variations in the moving speed of the head (FIG.20A) and the current flowing through the head driving circuit (FIG. 20B)at moving the head in the above embodiments.

Solid lines indicate variations in the head moving speed v and thecurrent I, respectively, with respect to lapse of time in a quick mode,corresponding to the quick modes in FIGS. 15, 16, 17 and 18.Chain-dotted lines indicate variations in the head moving speed and thecurrent, respectively, with respect to lapse of time in a silent mode,acceleration and deceleration being same as those in the quick mode andmaximum speed being limited at v1, corresponding to the silent modes inFIGS. 15 and 16. Broken lines indicate variations in the moving speedand the current, respectively, with respect to lapse of time in a silentmode, the maximum speed being not limited and the current atacceleration and deceleration being limited at I1 and −I1, respectively,corresponding to the silent modes in FIGS. 17 and 18. Minus current ismade flow for braking and in the high speed access mode a current ashigh as that at starting is made flow at stopping.

Beside them another silent mode is conceivable, in which both themaximum speed and the current at acceleration/deceleration are limited.

Further, although it is supposed in the above embodiment that there aretwo kinds of working modes, quick mode and silent mode, the system canbe so constructed that three kinds of modes, which are a normal(standard) mode, a quick mode, in which higher speed access is possiblethan in the normal mode, and a silent mode, in which lower speed andlower power consumption are possible than in the normal mode, or morethan three kinds of modes are selected by switching.

In the above embodiments, since the speed of the disk motor is constant,unless mode change is effected in the course, once the system is startedin a certain mode, operation of increasing the rotation speed of themotor upto a predetermined value for every access is unnecessary andtherefore no delay in the read/write operation attendant on theincreasing the rotation speed of the motor upto the predetermined valueis produced.

FIG. 21 is a flow chart for explaining working relation between the diskdevice and the device of higher rank according to the present invention.

At first the power source in the main body of the device of higher rankprovided with the disk device is switched on (701) and the power sourceof the power source of the disk device is switched on (702).

Directly after switch-on of the power sources the working mode is set byusing information stored in ROM and a stable state is established (703).Directly thereafter, information of the working mode at the terminationof the last operation stored on the surface of the disk is loaded tostore the information in the RAM (704). A stable working mode isestablished in the working mode based on the information stored in theRAM (705). At this time the normal mode setting intermediate propertybetween the quick mode and the silent mode is set previously in the ROM.

In case where the working mode of the disk device is changed (706), atfirst a list of the working modes stored in the ROM of the disk deviceis loaded from the device of higher rank (707). The loaded list of theworking modes is displayed on the display of the device of higher rankin such a manner that the working mode set for the preceding operationis specifically stressed, and the user selects one working mode (708).Together therewith, the information of the working mode stored in theRAM is replaced by information of the working mode selected by the userand in this way the working mode is established (709).

In case where the working mode is changed by the user as describedabove, it is waited that a stable working state is again established.

Thereafter file access from the device of higher rank to the disk deviceis started in the working mode thus set to effect required datatransfer.

Further, when termination processing of the device of higher rank begins(710), information on the last working mode stored in the RAM of thedisk device is recorded in a specified place on the surface of the disk(711), which is “the working mode of the preceding operation” used nexttime at restarting the device of higher mode.

When all the processings have been terminated, the power sources of thedevice of higher rank and the disk device are switched off (712).

Next, as still another embodiment of the present invention, an examplewill be explained, in which the disk device indicated in FIG. 16, 17 or18 is applied to a computer using both a commercial AC power source andan incorporated battery power source, e.g. a notebook type personalcomputer.

In general, concerning power supply form for a notebook type personalcomputer, when it is used as a portable computer, it utilizes anincorporated battery and when it is used in an office, etc., it utilizescommercial 100 V AC. In case where it utilizes the incorporated batteryas a portable computer, power consumption of the system has directinfluences on continuous utilization time. Since it can be said thatlonger continuous utilization time is more desirable, it can be saidthat a disk device having a smaller power consumption has a betterperformance. On the other hand, when 100 V AC is utilized as powersource, since it is not necessary to pay special attention on powerconsumption, in so far as power supply is not stopped, it can be saidthat a disk device, by which read/write of information is effected witha higher speed, has a better performance. Therefore, for a notebook typepersonal computer, it can be said that a disk device having a smallpower consumption when it is used as a portable computer, for which ahigh speed file access is possible if necessary, is convenient to use.

However, heretofore, there were only disk devices having either one ofthe properties or an intermediate property which is neither of them.This is because it is difficult technically to achieve a small powerconsumption and a high speed access at the same time.

Therefore, in the present embodiment, a disk device provided with aplurality of working modes described in the above different embodimentsis applied to notebook type personal computer so that the quick mode ofa high speed access is selected automatically when a commercial AC powersource is used as power supply of the personal computer and the attacheddisk device, while the silent mode of a low power consumption isselected automatically when an incorporated battery power source isused.

That is, there is disposed at first a detecting portion 37 for measuringvoltage of an external power source as shown in FIG. 5 in an electricpower receiving portion of the device of higher rank as a mechanism forsensing whether power is supplied from the external power source.Usually, in a notebook type personal computer, there is disposed a diodefor preventing reverse current from the battery to the commercial powersource and when the external commercial power supply is stopped, powersupply is automatically switched over to the incorporated battery. Thus,in case where it is sensed by the sensing mechanism that no power issupplied from the external power source, i.e. the device of higher rankis driven by the incorporated battery, a signal thus obtained ismonitored by the CPU in the device of higher rank, the CPU in the deviceof higher rank gives automatically the disk device a command to workwith the working mode (silent mode) aiming a low power consumption. Onthe contrary, in case where the sensing mechanism has sensed that poweris supplied from the external power source, the CPU in the device ofhigher rank gives automatically the disk device a command to work withthe working mode (quick mode) aiming a high speed file access. In thisway, the relation between the utilization form of the notebook typepersonal computer and the working mode of the disk device is such thatthe working mode of low power consumption is set automatically, when itis used as a portable computer, while the working mode of high speedfile access is set automatically, when it is used in a office.

However, when the operator wishes to change the working mode, he can setfreely at any time a desired working mode by inputting a working modechanging command e.g. by means of a keyboard.

As a magnetic disk device for realizing the present invention, a deviceusing a magnetic head having a negative pressure slider structure can beutilized. This magnetic head is in contact with the surface of the disk,when the magnetic disk remains immobile, but it keeps a constantfloating amount independently from the number of turns (in eitherworking mode), when the rotation speed of the disk is higher than apredetermined value.

Although, in the above embodiments, explanation has been made, using amagnetic disk device, the present invention can be applied as well to anoptical disk device and an opto-magnetic disk device.

Further the present invention is not restricted to those described inthe embodiments, but it includes various modifications in the scopedefined in the claims.

What is claimed is:
 1. An information storing device, comprising: adisk-shaped memory medium; a motor rotatably supporting the medium; amotor driving circuit to drive the motor; a read or write head; a headdriving mechanism to drive the head; a head driving circuit coupled tothe head driving mechanism; a CPU, coupled to both the head drivingcircuit and the motor driving circuit, including a head seek timeselecting function to select one of a plurality of seek modes accordingto a command from a higher rank device, and the CPU also including afunction by means of which a last seek mode among the plurality of seekmodes is activated when said information storing device has inputelectric power which is switched off accompanied by the switching off ofa power input of a device of higher rank that can access saidinformation storing device, wherein: if a first seek mode is selected,then said head driving circuit gives a first drive current to said headdriving mechanism, if a second seek mode is selected, then said headdriving circuit gives a second drive current to said head drivingmechanism, and a noise level of said information storing device when thefirst seek mode is selected, is greater than a noise level of saidinformation storing device when the second seek mode is selected.
 2. Theinformation storing device as defined in claim 1, wherein said motorrotates different rotation speeds respectively according to said firstseek mode and said second seek mode.
 3. The information storing deviceas defined in claim 1 further comprising a connector portion forreceiving the command from the higher rank device.
 4. The informationstoring device as defined in claim 1 wherein the higher rank device is ahost computer.
 5. The information storing device as defined in claim 1wherein the first seek mode is a quick mode effecting short time seekingand the second seek mode is a silent mode effecting low noise seeking.6. The information storing device as defined in claim 1 furthercomprising a current limiter to limit currents flowing through the headdriving circuit in order to set the different voltage according to theselected mode.
 7. The information storing device as defined in claim 6wherein the current limiter is disposed within the head driving circuit.8. The information storing device as defined in claim 6 wherein thecurrent limiter is disposed within the CPU coupled to the head drivingcircuit.
 9. A method of operating a disk drive coupled to a higher rankdevice, the disk drive having a disk-shaped memory medium, a motorrotatably supporting the medium, a motor driving circuit to drive themotor, a read or write head, a head driving mechanism to drive the head,a head driving circuit coupled to the head driving mechanism, and a CPUcoupled to both the head driving circuit and the motor driving circuit,comprising the steps of: selecting one of a plurality of seek modesaccording to a command from the higher rank device, wherein if a firstseek mode is selected, then the head driving circuit gives a first drivecurrent to the head driving mechanism, if a second seek mode isselected, then the head driving circuit gives a second drive current tothe head driving mechanism, and a noise level of the disk drive when thefirst seek mode is selected, is greater than a noise level of the diskdrive when the second seek mode is selected; switching off a powersource of the disk drive accompanied by the higher rank device beingswitched off; restarting the disk drive accompanied by the higher rankdevice being switched on; and establishing a last seek mode before theswitching off step.
 10. The method of operating a disk drive as definedin claim 9, further comprising: selecting another of a plurality of seekmodes according to a command from the higher rank device.